DESIGN AND NUMERICAL SIMULATION OF THz-FEL AMPLIFIER IN KYOTO UNIVERSITY

We have designed a relatively simple, compact and powerful THz-FEL (terahertz free electron laser) amplifier in Kyoto University. The target wavelength range of the amplifier is 150–340 μm, corresponding to 0.5-1.1 THz. The system consists of 1.6 cell photocathode radio frequency (RF) gun, THz wave parametric generator, focusing solenoid, transport line, and 120 cm long undulator with 30 periods. A start-to-end simulation in the institute of advanced energy Kyoto University has been conducted to estimate the performance of the designed system. Tracking of the electron beam from the photocathode RF gun up to the undulator entrance has been done using Parmela code while Genesis 1.3 code has been used to estimate the FEL interaction in the undulator. For feasibility study the FEL temporal distribution at resonance wavelength 186 μm was determined. The results show that 1250% amplification could be achieved in the resonance wavelength in the present design compared with the seed THz power. Details of the design and calculation conditions together with the performance test are presented in this paper.